Alpine Butterflies Research Articles

Effects of meadow suitability on female behaviour in the alpine butterfly Parnassius smintheus

Abstract 1. Many butterfly populations persist in networks of naturally fragmented habitat patches. Movement and reproductive decisions made by adult females are critical to the persistence of these populations because colonisation of extinct habitat patches in the network requires emigration of fecund adult females from their natal meadow and their subsequent establishment in the extinct patch.2. Movement and oviposition behaviours of mated Parnassius smintheus females released in suitable meadows (a good‐ and a poor‐quality meadow) and an unsuitable meadow were compared, to determine whether adult females consider meadow suitability for their offspring despite frequent oviposition events off the larval host plant.3. Bootstrap and correlated random walk analyses of female step lengths and turn angles demonstrated that females flew more randomly in the unsuitable meadow than in the suitable meadows. Although females tended to turn the sharpest angle between landing sites in the good‐quality meadow, and fly the smallest distance between landing sites and displace the smallest distance from the release site in the suitable meadows, no significant differences were detected in turn angle, step length, and dispersal rates between suitable and unsuitable meadows.4. Results from female flight observations and a caged oviposition study suggest that females lay significantly more eggs in suitable habitat than in unsuitable habitat despite not ovipositing on the host plant, and support the above findings.5. Movement and oviposition behaviours of adult female P. smintheus promote their retention within meadows that can support their offspring.

Genetic divergence and the Pleistocene history of the alpine butterflies Boloria improba (Nymphalidae) and the endangered Boloria acrocnema (Nymphalidae) in western North America

Allozymes were assayed at 20 presumptive loci in increasingly isolated populations of alpine butterflies in the Boloria improba species-group including the endangered Boloria acrocnema. Populations of this Holarctic group were sampled along the Rocky Mountain Cordillera from the Yukon Territory to Colorado. Samples from a more widely distributed and generalist butterfly, Boloria titania, were assayed at 18 presumptive loci for comparative purposes. Estimates of heterozygosity, percent polymorphic loci, mean number of alleles per locus, genetic identity, and distribution of regional and private alleles indicated that the current distribution of butterflies in the B. improba group is the result of a vicariance event. During the last Wisconsin glacial maximum (20 000 to 18 000 years BP) the range of ancestral B. improba was split into Alaskan refugial populations and southern glacial-margin populations. Subsequent dispersal into an ice-free corridor 12 000 to 10 000 years BP from the Alaskan refugial populations gave rise to British Columbia and Alberta B. improba populations. Results from B. titania support these findings.

ADAPTATIONS OF TERRESTRIAL ARTHROPODS TO THE ALPINE ENVIRONMENT

Summary1. The climate changes drastically above the timberline. Diverse adaptations have been evolved by insects and other terrestrial arthropods to survive the alpine environment. The fitness of each species depends on a combination of different factors in accordance with their special habitats.2. Morphological adaptations such as reduced body‐size, are known from a number of alpine insects, increasing their possibility to find sheltered microhabitats. Selection for reduced body size in Andean Phulia spp. butterflies is probably a result of their rigorous environment. Wing atrophy, which is also known in insects from other extreme environments, is widespread in alpine species. In several terrestrial arthropods the absorption of solar radiation is increased by melanism. Increased pubescence, protecting against the loss of heat, is known in alpine butterflies and bumblebees.3. Several behavioural adaptations are described. Thermoregulatory behaviour is important in many species to raise their body temperatures. Alpine butterflies orient the dark basis of their wings perpendicular to the rays of the sun. Body temperatures of 30 °C may be required for flight. To increase their activities many alpine terrestrial arthropods seek warmer microhabitats in the vegetation and under rocks. The adaptive advantage of nocturnal activity as observed in several species, may be to maintain the water balance or to avoid predation.4. Tropical alpine terrestrial arthropods are faced with special problems. The large diel temperature fluctuations require cold‐hardiness during the night and tolerance to heat during the day. Many species seek sheltered microhabitats under rocks and in vegetation.5. Due to low precipitation and high evaporation rates many mountain areas are extremely dry. High resistance to desiccation may be very important to alpine species, and in particular to tropical species. Rates of water loss at low relative humidities are comparable to those of desert arthropods.6. As an adaptation to the cold alpine summers several species of terrestrial arthropods require more than one year to complete their life‐cycles. Special to these species is their adaptation to low temperatures in two or more overwintering stages. In spite of their cold surroundings several species have univoltine life cycles, frequently combined with highly specialized adaptations. Increased metabolic rates as a compensation to low temperatures may be widespread in alpine species, but few data are available.7. Cold tolerance is of particular importance in temperature alpine species. Winter survival in Collembola and Acari depends on supercooling. Great seasonal variations have been observed in a number of species. Freezing tolerance is also known from alpine insects, e.g. in some species of beetles. At high latitudes alpine species must endure periods of up to eight or nine month at low temperatures during hibernation. Anaerobiosis is known from species that are enclosed in ice, with lactate as the main end product of metabolism.

Notes on the behavior and ecology ofReliquia santamarta,an Alpine butterfly (Lepidoptera: Pieridae) from the Sierra Nevada de Santa Marta, Colombia, with comparisons to Nearctic Alpine Pierini

Summary Reliquia santamarta is an unusual Pierine butterfly endemic to the Sierra Nevada de Santa Marta of northeastern Colombia, where it flies above 3500 m. Its biology is of particular interest because of the possibility that it might be a relict derived from the otherwise Holarctic Pieris callidice group, which it strongly resembles phenotypically. Its behavior was studied afield for comparison with Nearctic members of that group. Male R. santamarta are vigorous hilltoppers, assembling to topographic prominences, while females are frequently encountered at lower elevations. Flight patterns, thermoregulatory postures, and interactions between and within the sexes are all virtually identical to high‐montane and alpine Nearctic Pieris. The natural host plant was not determined. The role of seasonality in the biology of R. santamarta is discussed. Behavior data alone are inadequate to determine whether R. santamarta is closely related to or strongly convergent with the Nearctic taxa.

Characterization of electrophoretically cryptic variation in the alpine butterfly Colias meadii.

Enzyme polymorphism was characterized among the proteins of 14 loci of Coliae meadii by replicate electrophoresis in polyacrylamide gels of differing pore size. The results reveal a large number of variants, with a very skewed frequency distribution. A large fraction of the variants cannot be differentiated by electrophoresis in 5--7% acrylamide gels. This gel sieving approach permits an estimate of the relative contributions of charge and of conformation to electrophoretic mobility. Many of the variant proteins do not differ in charge. Most variants exhibit different degrees of interaction with the gel and presumably differ in conformation.

Enzyme Polymorphism and Adaptation in Alpine Butterflies

The high levels of enzyme polymorphism often detected by electrophoresis probably reflect on-going balancing selection. However, hypotheses of single gene heterosis (such as overdominance or environmental balance) do not seem adequate to account for this variation. To investigate this problem further, polymorphism was studied in Colorado butterflies of the genus Colias. Colias are easy to breed and study in the field and occupy a diverse array of habitats. Four species were studied: all were found to be highly polymorphic. Polymorphism at the a-glycerophosphate dehydrogenase locus occurred only when the species in question occupied a montane habitat; no polymorphism was seen in populations occupying alpine or lowland habitats. Three populations of C. meadii were examined in detail which encompass both alpine and montane habitats (crossing timberline); in one of them detailed demographic studies were carried out. In each such population, marked dines were observed in a-GPdH frequency, despite the swamping effects of migration within the population. At thirteen other loci a variety of different patterns of allele frequency are seen (some clinal, some uniform, some discontinuous), despite the fact that all loci were assayed in the same individuals. This result constitutes strong evidence of selection. There is clear evidence that particular alleles at the different loci preferentially associate together at specific locations along the line, different assemblages occurring at different locations. A hypothesis is presented that these represent integrated metabolic phenotypes, and that the enzyme polymorphism is a multi-locuis strategy to preserve that integration in a heterogeneous environment.

The Glacial Period and Geographical Distribution

PROF. ASA GRAY, in his very interesting lecture on the disribution of the forest trees of the northern temperate region (NATURE, vol. xix. p. 327), after pointing out the remarkable differences that exist between the forests of the eastern and western sides both of North America and the Old World, suggests that the great poverty of the European as compared with the Japan-Manchurian region in this respect was caused by the Mediterranean cutting off the retreat of the flora which then occupied Europe, as it retired, at the approach of the glacial epoch, before the ice from the north. This explanation derives considerable support from some other facts in geographical distribution. The most characteristic Alpine and Arctic butterflies of the Palaearctic region belong to the three genera, Parnassius, chionobas, and Erebia. Of Parnassius, Dr. Staudinger, in his latest catalogue (1871) enumerates fourteen Palaearctic species, of which three occur in North and Central Europe, ranging as far south as the Balkans, but always in or near high lands, about a dozen occur in temperate Asia, ranging as far east as the Amur, and probably as many in North America, where they also are truly Alpine butterflies. Of Chionobas one species (C. aello, confined to the Alps) occurs in Central Europe, whilst six or seven others range from Lapland over Russia and Siberia, Mongolia, &c., to the Amur, and there are numerous species in Arctic and Alpine North America. Of Erebia there are fortyfive Palaearctic species enumerated by Staudinger, and of these no less than twenty-five occur in the central Alpine chains of Europe. The genus likewise ranges all over temperate Asia, going as far south as the Himalayas and Moupin, and in North America is represented by a dozen or more species. Now, though an Erebia (E. Tyndarus, var.) occurs as far south in Europe as the Sierra Nevada, not a single species of any of these three genera occurs in North Africa, although the Atlas Mountains would seem eminently well suited for such Alpine insects. In this case, then, it seems clear that the same cause—the barrier of the Mediterranean—which in the case of the miocene flora of Europe prevented any further retreat south, has operated to prevent any similar southerly spread amongst the victorious invaders from the north which pressed on the retiring host.